Quality wool felt to minimize diffraction

[Omholt]

* Mod note: Title changed to 'wool' felt

I'm looking for wool felt to use on a baffel. 3-5 mm thick and it needs to look nice besides having good acoustic qualities.

Any suggestions?

 

[speakerdoctor]

I presume you are looking for wool felt. Here is a suggestion

DIFFRACTIONBEGONE REVIEW

 

[Omholt]

I presume you are looking for wool felt. Here is a suggestion

DIFFRACTIONBEGONE REVIEW

Yes. How embarrassing!

 

[speakerdoctor]

Not a problem Bjorn. I bet your english is much better than my Norwegian. 🙂

Actually, I admire those who post here who's native language is not english.

 

[xrk971]

Not the prettiest stuff but works well to control diffraction on tweeters. Scotchbrite scouring pads.

Here are the measurable results.

Smooths it out nicely and you can hear a difference too. It helps off axis response stay smoother.

More info here.
http://www.diyaudio.com/forums/full-range/280331-fr58ex-ac130f1-micro-fast.html

 

[Pallas]

Read David L. Ralph's stuff. IIRC he used SAE F13 felt for most of his diffraction experiments. Foam might be another alternative.

 

[Omholt]

Thanks for the replies.

I also need someone who can custom make a bigger piece of wool felt.

Foam probably isn't an option here. This is for a potential commerical speaker project and it needs to look nice.

 

[weltersys]

Bjorn,

Wool Felt carpet underlayment (a Google search found it is becoming popular again) comes in various sizes (and thickness), 6 foot width is typical.

Some of the examples looked nice, some definitely should be kept under the carpet 😉

Art

 

[speakerdoctor]

Not the prettiest stuff but works well to control diffraction on tweeters. Scotchbrite scouring. <snip>

A little improvement. I've studied this before and found you need at least 3/8 inch or more of needled felt to make a difference. Just read David Ralph's study. Also check out the the spicaspeakers enthusiasts page. IIRC, Jon Bau used horse saddle felt for his classic Spica TC-50 speakers and others.

Check out post #5 here and download the .pdf file.... SPICA TC-50 Restoration and Measurements - Other Speakers and Electronics - The Classic Speaker Pages Discussion Forums

 

[Jonathan Bright]

Interesting thread. Any chance a moderator or someone could go to the title of this thread and change "wood" to "wool". It is delightfully ambiguous at the moment and I nearly didn't look at it because I thought it WAS actually about wood.......
Btw there is a piece by Malcolm Hawksford (Essex Uni I think) on this subject in the Engineering Notes in a copy of the JAES from sometime in the '80s I think.
Sorry can't be more precise than that until I find my copy.
Cheers, Jonathan

 

[xrk971]

I've studied this before and found you need at least 3/8 inch or more of needled felt to make a difference.

It just so happens that Scotchbrite pads are indeed 3/8in thick. I found that adding the little 0.5in thick strips right around the tweeter like on LS3/5A helps a little more than just the flat pad around the tweeter. Scotchbrite pads are very porous, almost like reticulated foam so they are quite acoustically transparent yet reduce the diffraction ripples.

 

[speakerdoctor]

The thickness isn't the only key performance variable. I posted that number based on my experience with wool. Scotchbrite wasn't evaluated. However, I do suspect its density is quite a be lower than highly needlepunched wool padding. Density and fiber type are also important variables.

 

[Cal Weldon]

change "wood" to "wool".

We are most happy to. All we need is someone to report the post so we know you want it changed. We don't read every post in every thread.

It is changed now.

 

[Jonathan Bright]

Thanks Cal and a Merry Christmas to all the diyAudio crew for running a great site.
Cheers, Jonathan

 

[Omholt]

Read David L. Ralph's stuff. IIRC he used SAE F13 felt for most of his diffraction experiments. Foam might be another alternative.

I see that the felt he used and the other one he mentioned (F-11) were not of 100% wool.

I would think 100% wool would absorb better than something mixed with synthetic material. The density also comes into play. If it's very dense, it will reflect higher frequencies. But that I doubt that an issue with 100% wool with only 3-5 mm thicknesses.

I have found some here that uses 100% wool:
3mm Thick Virgin Merino Wool Designer Felt by the Yard – Aetna Felt
https://www.weircrafts.com/wool-felt/3mm-wool-felt.html
100% Wool Felt Sheets - 4mm thick - Blooming Felt
https://www.cloudcraft.co.uk/pure-wool-felt/thick-100-wool-felt
Woolfelt mixed colours - HOLLANDFELT

 

[fortitudine]

McMaster-Carr supplies wool for acoustic (and other) purposes...

McMaster-Carr

 

[Fitero]

I searched around for the best quality and price and bought one of these for my projects;

Off White 100 Wool Felt 12" Wide x 24" Long x 1 2" Thick Soft F 10 Duro Felt | eBay

You can dye the wool easily with locally sourced fabric dye. Here in North America, Rit is the most widely distributed it seems.

 

[Top Shelf]

Brand felt ltd. If you're ever in Canada.

 

[eyoung]

here u go...
Wool Felt Horse Saddle Pad 30" x 30" Heavy Duty 3 4" Thick USA | eBay

in the USA...

regards all, Elwood

 

[eriksquires]

Takes but a little....

* Mod note: Title changed to 'wool' felt

I'm looking for wool felt to use on a baffel. 3-5 mm thick and it needs to look nice besides having good acoustic qualities.

Any suggestions?

This is not nearly as thick, but I've had really good luck with the thin felt with PSA and without. Around the Focal speakers I was modding it really took out some peaks around 10k and another below.

I guess my point is, it didn't take much to work for me.

I just bought mine at the local Blick art supply store.

Best,

Erik